U.S. Pat. No. 2,280,851 to Leo Ranney, the disclosure of which is hereby incorporated by reference, discloses a system for collecting ground water that uses a vertically oriented caisson, combined with one or more well points that extend horizontally out from the bottom of the caisson in a radial pattern. This system is commonly known as a Ranney Collector System, and it has been used in water supply systems for municipalities and other large-volume water consumers. The design is primarily used adjacent to large bodies of surface water to collect water therefrom.
Despite the benefits of Ranney Collector Systems, they have several drawbacks. For example, the system requires a vertical caisson that is large enough in diameter to operate a horizontal drilling system at its base that allows drilling outwards radially through the sides of the caisson. Accordingly, there are limitations on the construction of smaller systems for use where water supply demands are less.
The system requires that a crew perform work at the bottom of a caisson, which is a confined space posing stringent health and safety threats to workers, and the system has limitations on the length of radial collectors that can practically be installed. The maximum horizontal collector length is approximately 250 feet. Also, the radial collectors are unguided and are not steered into position, meaning that they cannot be directed to follow high production zones, and the radial collector points extending from the caisson are not easily accessible for cleaning and maintenance.